Oh, exhaust bellows, they are such a pain in the ass.
Is this a new problem, or right from shipyard? Maybe you just have too much motion, and worn isolator in the exhaust trunking - these are checked by measuring them, they don't last forever. I remember having many problems on one ship, but can't remember what was done to fix it. On some bellows too, there is a particular way to install for proper gas flow, I'm sure you are aware. I will think of it some more, and maybe something will jar loose, in the mean time good luck.
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